Injection mould

ABSTRACT

For the purpose of producing, from thermoplastic plastic, fittings ( 15 ) or the like which have at least one annular groove ( 16 ) on the inside, an injection mould has an outer mould which can be divided in a parting line ( 20 ), a mould core ( 2 ) being axially displaceable along a mould half ( 1 ). A complementary mould bead for the annular groove ( 16 ) is formed by levers ( 6 ) carrying ring segments, and an actuating element ( 8 ) for swivelling the levers ( 6 ) is disposed in an axially displaceable manner in the mould core ( 2 ). A slider ( 14 ), which bridges the parting plane ( 20 ) of the outer mould and is connected to the second mould half ( 3 ), has guide grooves ( 91, 93 ) of differing obliqueness, in which there engage motionally lateral projections ( 101, 103 ) both of the mould core ( 2 ) and of the actuating element ( 8 ), said projections being disposed in the parting plane ( 20 ). A guide, which extends the opening stroke of the mould core ( 2 ), is formed at a distance from the parting plane ( 20 ), between the slider ( 14 ) and at least the mould core ( 2 ), said guide preferably comprising second, lateral projections ( 102, 104 ) and second guide grooves ( 92, 94 ).

The invention relates to an injection mould for producing, from thermoplastic plastic, fittings or the like which have at least one annular groove on the inside, said injection mould comprising an outer mould which can be divided in a parting plane, and comprising a mould core which is axially displaceable along a mould half of the outer mould and on which there is formed, for the annular groove, a complementary mould bead consisting of ring segments carried by levers, an actuating element for swivelling the levers being disposed in an axially displaceable manner in the mould core, and comprising a slider which bridges the parting plane of the outer mould, is connected to the second mould half and has guide grooves, of differing obliqueness, in which there engage motionally lateral projections both of the mould core and of the actuating element, said projections being disposed in the parting plane.

In EP 548 823 A it is disclosed that the extraction and insertion of the mould core is motionally coupled to the opening and closing of the outer mould. Provided for this purpose there is a slider which bridges the parting plane of the outer mould and has two lateral plates comprising guide grooves in which there engage projections of the mould core.

In order to extend the opening stroke, an embodiment makes provision whereby the guide grooves are formed in a telescopically extensible element.

According to DE 94 15 523 U, which discloses an injection mould of the type stated at the outset, the actuating element for prior swivelling of the levers of the mould bead is also included in the motional coupling between the slider and the mould core.

Since, in the closed position, the greatest forces have to be introduced into the mould core at the start of the opening stroke, the projections are disposed on both sides in an axial plane of the fitting to be demoulded, in which axial plane the parting plane of the outer mould is located, and assure an axial introduction of force from the slider moving perpendicularly to said parting plane. These projections, at the end of the opening stroke, are located at the end of the guide slots, the extent of the slider being limited in its direction of motion by the maximum possible extent of the overlap over the parting plane when the mould is in the closed position.

The object of the invention, therefore, is to achieve a greater opening stroke of the mould core in a simple manner. This is achieved, according to the invention, in that a guide, which extends the opening stroke of the mould core, is formed at a distance from the parting plane, between the slider and at least the mould core. The additional guide becomes effective only at the end of the usual, unmodified opening stroke, the dimension of the slider not being enlarged in its direction of motion, but instead a longer opening motion of the slider becoming possible, until the guide disposed at a distance from the parting plane has also attained its functional end.

The second guide likewise comprises, in particular, lateral projections on the mould core, and guide grooves, although transposal of this arrangement is also conceivable.

Provision is made, in a preferred embodiment, whereby the second, lateral projections engage in two guide grooves which extend parallel to the first guide grooves in lateral plates of the slider. This facilitates extended guidance, particularly if two projections are also provided on the actuating element, since the disposition of the projections and the allocation of the guide grooves can be optimally matched to the spatial conditions. In principle, however, it is conceivable for the first and second projections to slide, one behind the other and at a distance from one another, in the same guide grooves.

One guide slot per projection is a prerequisite for a further preferred embodiment, in which the width of the initial portions of the second guide grooves, which initial portions correspond with the first guide grooves, is greater than the diameter of the second projections. As a result, the introduction of force into the actuating element and into the mould core during the longer, first portion of the opening stroke is effected exclusively centrally, as hitherto, via the first projections, since in this portion the second projections do not bear on the walls of the second guide grooves. The second guide grooves taper at the transition to the extension guide, and the second projections take over the further guidance at least of the mould core for the end portion of its opening stroke, while the first projections come out of the first guide grooves, which widen from the transition onwards and preferably end in the form of a funnel.

Second projections and second guide grooves in the slider are preferably also assigned to the actuating element for swivelling the levers which form the mould bead, so that the slider has four guide grooves which are parallel in pairs on each plate, a respective projection for the guide extension being provided, at a distance from the parting plane, on the mould core and on the actuating element.

The extension guide on the actuating element can also be omitted, since the additional axial displacement of the actuating element is not necessary once the levers have been swivelled inwards, and the annular groove in the fitting has been released. In this case, the distance that develops, at the start of the opening stroke, between the mould core and the actuating element would lessen again during the extension stroke.

Further details of the invention are now explained with reference to the drawings, wherein:

FIG. 1 shows a longitudinal section through a closed injection mould,

FIG. 2 shows a partially sectional view from the left in FIG. 1,

FIG. 3 shows a section, corresponding to FIG. 1, following the release of the levers of the mould bead,

FIG. 4 shows the section corresponding to FIG. 1, with a mould core displaced over a first portion of the opening stroke,

FIG. 5 shows the section corresponding to FIG. 1, in the extended end position, and

FIG. 6 shows a detailed view of the guide grooves of a second embodiment.

An injection mould consists of an upper mould half 3 and a lower mould half 1, the upper mould half 3 being divided from the lower mould half 1 along a parting plane 20, and able to be raised upwards. Connected to the upper mould half 3 is a slider 14, whose two lateral plates 10, in the closed mould according to FIG. 1, project as far downwards as the lower mould half 1. Projections 101, 103 provided laterally on the mould core 2 are guided in guide grooves 91, 93 of the part and of an outer part which encompasses the latter in the manner of a sleeve, and which is firmly connected to a mould ring 4.

Levers 6 are disposed in a circle and have ring segments on their outer ends that form an annular core bead, when the levers 6 are swivelled-out according to FIG. 1. When the levers 6 are in the swivelled-out state, their inside is supported by a locking ring 5. This locking ring 5 can be actuated by at least one tie rod 7, which participates in the motion of an actuating element 8.

If the upper mould half 3 is raised from the lower mould half 1, the guide grooves 91, 93 in the plates 9 move relative to the projections 101, 103. This results, firstly—as shown by FIG. 3—in a displacement of the actuating element 8 on a slide strip 12 of the lower mould half 1. Slide angles 13 (cf. FIG. 2) prevent the actuating element 8 from being raised during this displacement. The transition from the position according to FIG. 1 to that according to FIG. 3 causes the locking ring 5 to be displaced relative to the levers 6. The levers 6 are thereby folded inwards, since the locking ring 5 strikes against the orthogonally projecting second arm of the levers 6. The mould core 2 can then be axially displaced.

If the upper mould half 3 moves out of the position according to FIG. 3 into that according to FIG. 4, the mould core 2 is also displaced, together with the mould ring 4 encompassing the levers 6, as a result of which the injection-moulded part 15 is fully released. As evident from FIG. 4, in this position the projections 101, 103 are at the lower end of the slider 14 that is raised with the upper mould half 3 and, upon further raising of the upper mould half 3 they come out of guide grooves 91, 93, such that they cannot effect any further displacement of the mould core 2 and of the actuating element 8. The plate 9 is therefore provided with two guide grooves 92, 94, which respectively have an initial portion 96, 98, running parallel to the first guide grooves 91, 93, and an end portion which extends the guide. Since the second guide grooves 92, 94 likewise end at the lower edge of the plate 9, their start is located higher than the start of the first guide grooves 91, 93.

Second, lateral projections 102, 104, which are disposed at a distance from the parting plane 20, above the first, lateral projections 101, 103 on the mould core 2 and on the actuating element 8, engage in the second guide grooves 92, 94. As evident from FIG. 4, when the first projections 101, 103 come out of the first guide grooves 91, 93, the second projections 102, 104 are at the transition from the initial portion 96, 98 to the end portion 97, 99, and take over the further guidance of the mould core 2 and of the actuating element 8 to the end of the extended opening stroke, as evident from FIG. 5.

FIG. 6 shows a second embodiment of a plate 9 of the slider 14, in which the width of the guide grooves 91, 92, 93, 94 differs over its length. The second guide grooves 92, 94 are wider over the initial portion 96, 98 than the first guide grooves 91, 93, which thereby cooperate without influence with the first projections 101, 103, almost over their entire length, to the opening which widens in the form of a funnel, with the result that the opening forces are introduced centrally into the actuating element 8 and the mould core 2 via the first projection 101, 103 located in the parting plane 20. In the subsequent end portions 97, 99, the second guide grooves 92, 94 are narrower than in the initial portions 96, 98, and take over the guidance of the mould core 2 and of the actuating element 8, via the projections 102, 104. 

1. Injection mould for producing, from thermoplastic plastic, fittings (15) or the like which have at least one annular groove (16) on the inside, said injection mould comprising an outer mould which can be divided in a parting plane (20), and comprising a mould core (2) which is axially displaceable along a mould half (1) of the outer mould and on which there is formed, for the annular groove (16), a complementary mould bead consisting of ring segments carried by levers (6), an actuating element (8) for swivelling the levers (6) being disposed in an axially displaceable manner in the mould core (2), and comprising a slider (14) which bridges the parting plane (20) of the outer mould, is connected to the second mould half (3) and has guide grooves (91, 93), of differing obliqueness, in which there engage motionally lateral projections (101, 103) both of the mould core (2) and of the actuating element (8), said projections being disposed in the parting plane (20), characterized in that a guide, which extends the opening stroke of the mould core (2) is formed at a distance from the parting plane (20), between the slider (14) and at least the mould core (2).
 2. Injection mould according to claim 1, characterized in that the guide which extends the opening stroke has second, lateral projections (102, 104) on the mould core (2) and preferably also on the actuating element (8), at a distance from the first projections (101, 103).
 3. Injection mould according to claim 2, characterized in that the second, lateral projections (102, 104) engage in second guide grooves (92, 94) which extend parallel to the first guide grooves (91, 93) in lateral plates (9) of the slider (14).
 4. Injection mould according to claim 3, characterized in that the width of the initial portions (96, 98) of the second guide grooves (92, 94), which initial portions correspond with the first guide grooves (91, 93), is greater than the diameter of the second projections (102, 104).
 5. Injection mould according to claim 1, characterized in that the first guide grooves (91, 93) for the first projections (101, 103) disposed in the parting plane (20) end in the form of a funnel.
 6. Injection mould according to claim 2, characterized in that the first guide grooves (91, 93) for the first projections (101, 103) disposed in the parting plane (20) end in the form of a funnel.
 7. Injection mould according to claim 3, characterized in that the first guide grooves (91, 93) for the first projections (101, 103) disposed in the parting plane (20) end in the form of a funnel.
 8. Injection mould according to claim 4, characterized in that the first guide grooves (91, 93) for the first projections (101, 103) disposed in the parting plane (20) end in the form of a funnel. 